Servomotor governor



Jan. 7, 1941. J. EHRHART I 2,227,427

SERVO-MOTOR GOVERNOR Filed April 1, 1957 //7 ventofi:

t power entitle. For

Wtltente flan V 194i %t,,tt'l,ttl snnvoinotnn eo tnnno lie Ehrhnrt, menthol, metnlnny, nsttgnor to;

eurntion ed New itter ltpnitention itnrllll Mitt, desist Woo ltt itlt tin Genny ltnrll to Mitt w to the rotating weights and springs, and slides nitinlly when the eunilllrrilun is altered. The non rotutine ntllnstine seer oi the governor, which orntes the control menus for the wrvo motor, is actedon try the eovemer sleeve. in

fiwortler to he the operation ot the governor etnhle, it is well known that there must he in udtlitlon e. return of the movements of the servolnotor to the servomotor control means in such why that a certain speed is allotted to every position ot the servoxnotor and vice verse.

'll'nrious iorms oi mechanical couplings have loeen employed between the governor sleeve and nervomotor to effect the return movement and, ntnnlly, some part or the mechanical coupling could be adjusted manually to determine the usually included a relatively critical operating speed or the governor system. "The governors and the mechanical couplings have urts, and the designs have been such as to give riseto substantial frictional resistances and to lost motion or play between connected parts,

object o! the present invention is to provide an scrvomotor governor which is characterized by treedom from pivoted mechanical linkages in the governor and in the motion-transfer elements that couple the governor and servomoior. An object is to provide a servomotor governor of the type stated which includes a fluid coupling dor enacting-the the governor. A furtherobject is to provide a servomotor governor in which the mechanism tor effecting the return movement and also the manually adjustable devices for setting the operating speed exert .torces substantially axially oi the governor sleeve.

The present invention consists in utilising. as the revolutionmeasuring means such a linkless hot spring governor and in effecting the return as well as. the adjustment or the speed by forces acting axially on the sleeve thereof. In contra.-- distinction to hitherto known designs the advantase is obtained that not a single link or the like is required in the whole device; so that all friction and even the slightest play is avoided. The precision of the governing is therefore better than ether-which, tor

large number of return or follow-up adjustment of port 14 in'lts to the original ll Wi WW) he more ole ly understood, reference is rnadeto the oceeln my ling dirttwinu 'tvhleh llluetrntet dttmn o l t and icy tinyotenple one ca in sold the, t spring tot-- tageouely tllen tllthite ttxoothorinontal, end t is the nototinn sleeve tltnt its endowed hit-the, non rotntintr yoke or collects at the endein stirrun -shnped ill! it which it t neet m to the control slide vnive t ct the'ley servo; motor it. at pressure t eontrolslide votive t hows tnnnd out, n serous lmiiented. .1 v To one end ot piston rod ot the serumlis rigidly joined the cone M e reeulotina valvet which cone routes the new oi the driving to the power engine in is not shown) At the otherend the picture rodearries an auxiliary piston which moves in the chamber 6 and chests-the return in the toilowfling r: The cylinders t and 8, nndulso the connecting pipe I ure'entirelyflllcd with ,oil as the cylinder t is within the oil J3 and substantially below the level n! the top of the chr walls It. so that every displacement or the piston lmults in a corresponding displaceanent oi the return pm 0. Between the pisston and the stirrup-shaped member II. is disposed a return spring, under tension.' Depending on the position oithe piston]. said spring exerts a certain force on the stirrupahap'ed member H and thus on the sleeve '2.

the direction at the whereby the speed of equilibrium of the governor is influenced in accordance with the position o! theservomotor l. 'I'hcpistofllhasasmnlllcak humthe eldest of which isgthat the tension of the sprin: ll "gradually-vanishes during and after every operatiomso that the aoyernor always. exactly returns min 'Ifhepllton I alsoiunctlona as an oil brake prgdemper to preclude excessive displacements oithe controlslidc-vulvc 3 upon in the speed oifthc governor. The oil level in chamber ll thua eliminates the danger that during the downward movement or the piston l' atmospheric air will be drswn throuih theopeninz ll intothechamherl andintothc tube I, whereby the hydraulic rod system milht become unrilid.

To the stirrup-shaped member is also secured w noise or tnneltm is tid- M of equilibrium of the governor.

a speed spring IS, the right-hand end of which is rigidly joined to a spring plate I 6. The tension of the spring l5 can be adjusted in accordance with the desired speed by means of a spindle-ll and nut I8.- The spring I5 is secured against rotation both on the spring plate l6 and on the stirrup II, and thus prevents any rotation of the'stirrup it with the sleeve 2 around the axis of the governor. Since the governor I rotates and the collar 2a does not, a frictional torque is set up on the collar 2a the magnitude of which is dependent on the forces exerted at the time in question by the spring l5 and, during control intervals, the spring It). This torque endeavours to turn the collar 20. together with the stirrup ll about the axis of the governor, and in order to prevent such a rotation the spring I5 is so secured at its two ends against rotation that it must transmit the frictional torque from the stirrup H to the spring plate Hi. This frictional torque, which arises from the fact that both the return and the adjustment of the speed are effected by forces which act in an axial direction on the sleeve 2, is thus transmitted 'on the one side to the driving shaft through the rigidity of the band springs of the governor I, and on the other side to the spring plate I6 through the spring l5 which is secured against rotation, In both cases the moment is taken up in such a way that no friction can occur which might hinder the movement of the sleeve in the axial direc tion. The loading of the sleeve can therefore be made as high as desired without detracting from the sensitivity of the apparatus.

If for example, the spring plate I6 be displaced to the left by turning the spindle 11, there is induced on the governor sleeve 2 a force also directed towards the left, whichreduces the speed The arrangement may also be such, or the spring Hi can be made sopowerful that the band springs of the governor I, which are straight in the unstressed state, can also be brought into the position of equilibrium shown in the drawing when the machine is stationary, in which position the edges of the control slide valve 3 cover one'another. With this arrangement it is thus possible to adjust the speed from its maximum value down to a state of rest, and to drive the power engine,

with automatic regulation at any desired speed between the state of rest and the maximum value.

I-claim:

1. In a servomotor governor, the combination with speed measuring means comprising a shaft, a rotating governor sleeve and means supporting the same for axial movement, a plurality of normally flat jointless leaf springs each secured to and rotatable with said shaft and'said governor sleeve, and a. non-rotatable collar in en-- gagement with said sleeve for axial displacement thereby, of a control member, means actuated by axial movement of said governor sleeve and collar for adjusting said control member, means actuated by movement of said control member for returning the governor sleeve to normal position after axial movement thereof, said returning means including spring means coaxial with said'governor sleeve, and torsion spring means secured respectively to said non-rotating collar and to a non-rotating member to balance the frictional torque developed by the rotation of said governor sleeve in engagement with said collar.

2. In a servomotor governor, the invention as claimed in claim 1, in combination with means manually adjustable to displace said non-rotating member towards and away from said sleeve, thereby to adjust the critical speed of said speed measuring means.

3. The invention as claimed in claim 1, wherein said shaft and governor sleeve are horizontal;

and said returning means includes an oil chamber, a cylinder coaxial with said governor sleeve and within and substantially below the upper edge of said oil chamber, and a piston slidable in said cylinder, said spring means of the returning means being connected between said piston and said governor sleeve.

4. A servomotor governor comprising a speed measuring device including a governor sleeve and a plurality of normally fiat leaf spring members for displacing said sleeve axially in response to rotation of said spring members, the axis of said governor sleeve being substantially horizontal, a cylinder coaxial with said governor sleeve, a chamber formaintaining said cylinder filled with oil, a. piston in said chamber, an inverted stirrup carried by said governor sleeve and having one leg depending into said chamber, a spring between said piston and said leg,-

a control member, fluid pressure means including a valve actuated by said stirrup for displacing said control member, and a hydraulic transmission between said control member and piston for displacing said piston upon a' displacement of said control member.

5. A servomotor governor as claimed in claim 4, in combination with manually adjustable means forgexerting a force upon and axially of said governor sleeve, said adjustable means comprising a plate surrounding said cylinder, means manually operable to adjust said plate axially of said cylinder, and a coiled spring coaxial with said plate and cylinder, the ends of said coiled spring being secured to said stirrup and to said plate.

6, In a control system, the combination with a centrifugal governor consisting of leaf-springs,

brake axially spaced from said governor and comprising acylinder and piston coaxial with said governor sleeve, spring means connected at one 'end to said non-rotatable member and at the other end to said piston, hydraulic means for transmitting the movement of the servomotor to said oil-brake to displace said piston upon a displacementjof said servomotor, whereby said piston and spring means are adapted to return said governor sleeve to normal position after axial movement thereof, and resilient means to balance the frictional torque developed by the rotation of said governor sleeve in engagement with said member. JOSEF HART. 

